Not that there wasn't a celebratory mood in the air Friday night at the DCU Center, as jam-band favorites Phish careened through a sprawling, more than three and a half hour-long set (including a roughly 20 minute intermission) that touched on elements of blues, folk and rock. But where one might have expected to have been met with joyous abandon — the wavy, free-form hippie dances of countless movies — what was found was a sardine-packed room filled with rapturous swaying and an often startlingly intense focus on the music. In some ways, there was a reverent quality to the whole thing, which was both beautiful and a little unsettling.

This being my first Phish concert, and being largely unfamiliar with the band's catalog, one thing became clear as soon as the music began: Everyone around me knew all the words, knew all the cues. In a lot of ways, it was like attending an unfamiliar church: You feel awkward when you're the only one who doesn't know when to sit, kneel or stand, who doesn't have the hymns memorized. But that doesn't mean there's not a power there, a sense of something greater than just music in a room.

Kicking off the night with a cover of blues legend Son Seals' "Funky B***h," a surprisingly straightforward blues piece from a band with a reputation for going off into space. But that trek was coming, and as the musicians transitioned into an original, "Wolfman's Brother," it was evident that the band was taking the audience on a journey, and it was unclear exactly where it all would land. Well, unclear to me. Evidently, everyone else had looked at the maps beforehand.

Very early in the show, the lines between individual songs became permeable, and it was unclear where one song ended and another began. Singer-guitarist Trey Anastasio, drummer Jon Fishman, bassist Mike Gordon and keyboardist Page McConnell have an incredible sense of synchronization on stage. In a lot of ways, the whole thing was more reminiscent of jazz than it was rock, with its free-form improvisations that spiraled out into the ether, which seemed to break away cleanly from the structure of whatever song the band was performing, but somehow always managed to land at exactly the right place, either folding back into the song they began with — particularly impressive on the band's second-set opener, "Waves" — or pivoting to the next song.

Indeed, one has a feeling the band would play the entire show straight through without stopping if they thought they could get away with it. There wasn't really any talking on stage, no chatty banter, save a moment at the beginning of the second set where Anastasio was thrown a Red Sox jersey. Stopping at all — whether it be between songs or pauses within songs — served more to cause an effect, to jar the audience, than to denote an ending. This is a journey, after all. The destination's not the point. When Anastasio holds the last note of "Wilson" for an uncomfortably long time, the crowd hangs onto the sound until the end, erupting when it's gone.

While there's a great psychedelic element to the music — definitely in play on songs such as "The Curtain With" — it's not entirely edgeless. The band gives the audiences touchstones along the way — a cover of Talking Heads' "Cities" was greatly appreciated, a bit of solid ground in this unfamiliar territory, even if it was both odd and delightful to hear it reshaped into a long-form blues number.

And the second set veered more fully into rock 'n' roll territory, the band not relinquishing its trademark feel and musical wanderlust, but upping the tempo and providing some sharper corners. Songs such as "Backwards Down the Numbers Line" had a touch of pop structure to them, a brightness that was easy to hook into. And as the set progressed, transitions between songs became more fractious — the jam on "Dirt" devolving to Anastasio whistling, followed by a noise-band-style bit of discord, into a rocking little number, "Down With Disease." While one suspects a diehard Phish phan might disagree, moments such as this were among the most electrifying, where the audience's trance is broken, the hypnosis replaced with a surging, joyous vitality.

And perhaps here is where the road was headed all along, but Phish takes a winding road to get to this place, and honestly, it's a little demanding. To really appreciate this music, one needs to give oneself over to it completely, to sustain focus on its meandering for a long period of time. I'm not entirely sure I'm capable of that. I have a very noisy head. But the rewards of that focus and attention were self-evident as the band closed out its second set on a rocked out note with the bracing songs "Cavern" and "Run Like an Antelope," a pairing that was cathartic and energizing.

It's funny. So much of this music is clearly a communal experience, very much intended to be shared among a large crowd, but there are also large stretches of it where the listener is very much alone with the music, particularly on those long jam sessions. In those moments, it seems that nothing else exists. And that pays off at the end, too, as rock begins to permeate the set, forcing the audience together again.

There was nothing spacey when the band returned for a four-song encore, which included the Osborne Brothers classic "Rocky Top" and Led Zeppelin's "Good Times Bad Times." There was singing and dancing, a positive energy and joy that rang throughout the DCU Center. The meditative states of some of the earlier stretches banished, leaving the listener very, very much awake.